• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.2
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• pp.109-114
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• 2009

Absorption spectra for a quantitative analysis of actinide elements such as U(VI) and Pu(V) were measured by using a liquid waveguide capillary cell (LWCC) which has an optical path length of 1.0 meter. In order to investigate radioactive elements, a LWCC is installed in a glove box and is coupled to a spectrophotometer with optical fibers. Limits of detection (LOD) for the system were determined as 0.74 and 0.35 M with molar absorption coefficients of 8.14${\pm}$0.07 (414 nm) and 17.00${\pm}$0.16 (569 nm) $M^{-1}cm^{-1}$ for U(VI) and Pu(V) ions, respectively. The measured LOD values are about 30 times more sensitive when compared to those achievable by using a conventional quartz cell with an optical path length of 1.0 cm. As an application with an enhanced sensitivity, a quantitative analysis for micromolar concentrations of Pu(V) has been performed to decrease the uncertainty in the formation constant of the Pu(VI)-OH complex.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1976-1980
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• 2010

A simple and reliable method has been developed to selectively separate and concentrate trace amounts of Fe(III) ions from water and food samples by using flame atomic absorption spectrometry. A new reagent, 5-hydroxy-4-ethyl-5,6-di-pyridin-2-yl-4,5-dihydro-2H-[1,2,4] triazine-3-thione, was synthesized and characterized by using FT-IR spectroscopy and elemental analysis. Effects of pH, concentration and volume of elution solution, sample flow rate, sample volume and interfering ions on the recovery of Fe(III) were investigated. The optimum pH was found to be 5. Eluent for quantitative elution was 10 mL of 2 M HCl. The preconcentration factor of the method, detection limit (3s/b, ${\mu}gL^{-1}$) and relative standard deviation values were found to be 25, 4.59 and 1%, respectively. In order to verify the accuracy of the method, two certified reference materials (TMDA 54.4 lake water and SRM 1568a rice flour) were analyzed. The results obtained were in good agreement with the certified values. The method was successfully applied to the determination of Fe(III) ions in water and food samples.

• Journal of the Korean Chemical Society
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• v.38 no.3
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• pp.214-220
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• 1994

A glow discharge atomic absorption system for the direct analysis of conducting solid samples has been designed and constructed. An arrestor made of machinable ceramic which is a main component for confining the discharge between cathode and anode is modified to have a better stability in discharge. Discharge voltage or current, shape of arrestor, pressure, and gas flow rate can be controlled by an ADC/DAC board with a personal computer. The effect of discharge parameters such as discharge voltage, pressure, and gas flow rate on the sample loss rate, absorbance, and the surface morphology of sample by SEM has been studied to find optimum discharge conditions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.1
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• pp.1-8
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• 1986

Authors investigatigated the analysis heavy metals in corps at the Mankyung river area. Samples were digested with Cone. nitric acid and Cone. hydroc hrorico acid and analyzed by Varian 875 Atomic Absorption Atomic Absorption Spectrophotometer in 1984. The results were as follows: The contents of heavy metals in rice were in the range of $0.41{\sim}5.15,\;1.12{\sim}5.18,\;10.65{\sim}14.54,\;24.15{\sim}35.41ppm$ for Pb, Cu, Mn, Zn respectively. Those in barley were in the range of $0.48{\sim}0.8,\;1.39{\sim}2.81,\;9.69{\sim}14.89,\;30.14{\sim}34.84ppm$ for Pb, Cu, Mn, Zn respectively. Those in kidney bean were in the range of $0.06{\sim}0.13,\;3.65{\sim}6.25,\;.65{\sim}12.15,\;51.25{\sim}65.69\;ppm$ for Pb, Cu, Mn, Zn respectively. Those in corn were in the range of $0.59{\sim}0.89,\;2.15{\sim}2.83,\;6.01{\sim}10.15,\;29.31{\sim}36.15ppm$for Pb, Cu, Mn, Zn respectively. We might be concluded that the above values of heavy metals contained in crop at the sites near to Mankyung river were serious partially.

• Bulletin of the Korean Chemical Society
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• v.25 no.8
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• pp.1133-1136
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• 2004

The need for highly reliable methods for the determination of trace metals is recognized in analytical chemistry and environmental science. A method based on the cloud-point extraction (CPE) technique for the trace analysis of Pb and Cu in water samples is described in this study. The analytes in the initial aqueous solution are complexed with pyrogallol, and 0.1%(w/v) Triton X-114 is added as surfactant. Following phase separation at $50^{\circ}C$, based on the cloud point of the mixture and dilution of the surfactant-rich phase with acidified methanolic solution, the enriched analytes are determined by flame atomic absorption spectrometry. After optimization of the complexation and extraction conditions, the enrichment factors of Pb and Cu were found to be 72 and 85, respectively. Under optimum conditions, the preconcentration of 60 mL of samples in the presence of 0.1%(w/v) Triton X-114 permitted the detection of 0.4 ${\mu}gL^{?1}$ of Pb and 0.05 ${\mu}gL^{?1}$ of Cu. The proposed method was applied successfully to the determination of Pb and Cu in water samples.

• Analytical Science and Technology
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• v.20 no.6
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• pp.516-523
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• 2007

Purification of silica mineral has been investigated by acid leaching of pulverized silica. A series of studies has been carried out on the effect of leaching silica powder as a function of the leaching time at the constant temperature of $80^{\circ}C$ in oxalic acid, aqua regia, and two mixed acids of HF/HCl, $HF/HNO_3$. The impurities of silica and leachantes were measured by neutron activation analysis (NAA), inductively coupled plasma atomic emission spectrometry (ICP-AES), atomic absorption spectrometry, x-ray fluorescence (XRF) method and wet analysis (WA). Certain metals, such as sodium, calcium, iron, aluminium and titanium, have been found in concentrations of hundreds or even thousands of mg/kg. Comparison of purification processes of silica and analytical methods of impurities in the silica was conducted in this study.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.75-78
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• 2015

A growing body of evidence has been supporting the existence of so-called "dark molecular gas" (DMG), which is invisible in the most common tracer of molecular gas, i.e., CO rotational emission. DMG is believed to be the main gas component of the intermediate extinction region from Av~0.05-2, roughly corresponding to the self-shielding threshold of $H_2$ and $^{13}CO$. To quantify DMG relative to $H{\small{I}}$ and CO, we are pursuing three observational techniques; $H{\small{I}}$ self-absorption, OH absorption, and THz $C^+$ emission. In this paper, we focus on preliminary results from a CO and OH absorption survey of DMG candidates. Our analysis shows that the OH excitation temperature is close to that of the Galactic continuum background and that OH is a good DMG tracer co-existing with molecular hydrogen in regions without CO. Through systematic "absorption mapping" by the Square Kilometer Array (SKA) and ALMA, we will have unprecedented, comprehensive knowledge of the ISM components including DMG in terms of their temperature and density, which will impact our understanding of galaxy evolution and star formation profoundly.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1367-1379
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• 2020

The small modular sodium-cooled fast reactor (SMSFR) is an important component of Generation-IV reactors. The objective of this work is to improve the reactivity control in SMSFR by using innovative systems, including burnable poisons and optimized control rods. SMSFR with MOX fuel usually exhibits high burnup reactivity loss that leads to high excess reactivity and potential fuel melting in control rod withdrawal (CRW) accidents, which becomes an important constraint on the safety and economic efficiency of SMSFR. This work applies two types of burnable poisons in a SMSFR to reduce the excess reactivity. The first one homogenously loads minor actinides in the fuel. The second one combines absorber and moderators in specific assemblies. The influence of burnable poisons on the core characteristics is discussed and integrated into the analysis of CRW accidents. The results show that burnable poisons improve the safety performance of the core in a significant way. Burnable poisons also lessen the demand for the number, absorption ability, and insertion depth of control rods. Two optimized control rod designs with rare earth oxides (Eu₂O₃ and Gd₂O₃) and moderators are compared to the conventional design with natural boron carbide (B₄C). The optimized designs show improved neutronic and safety performance.

• Journal of Radiation Industry
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• v.8 no.1
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• pp.17-22
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• 2014

In this study, we prepared CdTe/CdS solar cells using a thermal vacuum evaporation method. In particular, $CdCl_2$ treatment was attempted using this same method at $400^{\circ}C$ for 30 min. The prepared CdTe/CdS solar cells were investigated using Fouier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FE-SEM), and a solar simulator system including light absorption properties, morphological properties, and power conversion efficiency (PCE). In addition, we investigated the gamma-irradiation treatment at dose rates of 0 Gy, 500 Gy, 1 kGy, 10 kGy, and 30 kGy. The characteristics of gamma-irradiation treatment were studied based on the same method described above. In particular, it showed increased values as 0.826% higher than the non-irradiation of 0.448% from PCE analysis.

• Journal of the Korean Chemical Society
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• v.29 no.2
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• pp.129-136
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• 1985

In the atomic absorption spectrometry using an air-acetylene flame, the interferences of Zr, Sn, Al, Sb, $SO_4^{2-},\;VO_3^-,\;and\;SiO_3^{2-}$, on the calcium absorption and the repression of this interference by the addition of cerium have been studied. The interference by Zr, Sn, Al, Sb, $SO_4^{2-},\;VO_3^-,\;and\;SiO_3^{2-}$ existed as the same concentration as calciurn ($3.0 {\times} 10^{-4}$M) in the sample solution are completely released by the addition of cerium twice as much as interfering cation. The interferences by the mixed interfering cations (Zr, Sn, Al and Sb) and by the mixed interfering anions ($SO_4^{2-},\;VO_3^-,\;and\;SiO_3^{2-}$) are larger than by each interfering cation and anion, and the releasing effect by cerium ($1.5 {\times} 10^{-2}$M) is effective up to some degree of the concentration of mixed interfering cations and of mixed interfering anions. The releasing effect by cerium to the mixed solution of interfering cations and anions is applicable to quite wide range of concentration.